Sewing machine motor controller



June 11, 1935. H L zABRlsKlE 2,004,496

SEWING MACHINE MOTOR CONTROLLER Filed Jan. 8, 1932 Patented June 11, 1935 UNITED STATES PATENT E OFFICE 2,004,496 l SEWING MACHINE MOTOR CONTROLLER Henry L. Zabriske,Westleld-, N. J., assignor to The S beth,

inger Manufacturing Company, Eliza- N. J., a corporation of New Jersey Application January 8, 1932, Serial No. 585,409

4 Claims.

This invention relatesA to motor-driven sewing machines equipped with a controller and speed, the machine will not start when the controller is shifted from off position to the limiting position determined by the stop. This is be- Hence it is of the nature heretofore proposed, for the operator to give the maa controller, such as heretofore fitted with a stop, is that the variable resistance element comprises a series of contact buttons over which plays a movable conrequired.

the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Fig. 1 is a front elevation of a sewing machine motor-controller embodying the invention. Fig. 2 is ya side view of the same. Fig. 3 is an enlarged section on the vline 3 3, Fig. 2, and Figs. 4 and 5 are perspective views of an element of the controller-operating draw-bar.

The invention is shown as embodied in a carbon compression type motor-controller or rheostat such as disclosed in the patent to Chason, No. 1,792,813, of Feb. 17, 1931. This controller has an operating draw-bar which is connected by a rod to a treadle-plate enabling the opera- 1 tor to nicely control the speed of the sewing machine to meet the particular sewing requirements.

Such a controller comprises a casing including a base l and removable cover 2 Within which d and upon the base l is mounted the carbon type rheostat having the usual porcelain body 3 formed with spaced wells or chambers 4 for the stacks of carbon resistance disks 5 which substantially ll the Wells 4 and are electrically connected to the terminals 6. The stacks 5 also comprise the compression heads 'i which are bridged by the bow-spring contact- Rising from one end of the base I is an end through which passes the draw-bar H connected at its inner end to the hollow rectangular cross-head I2 the ends I3 of the legs of which are directed'toward one another but are spaced apart. Recovery springs It serve to restore the cross-head l2 and drawbar il to initial or non-running position with the cross-head portions I 3'contacting with the stop-screws l5.

From the centers of the bow-spring 8 and backing spring 9 there extends in line with the draw-bar H a pull-rod I6 having a screwthreaded end carrying an adjustable nut Il whose shank passes through the space between the ends of the cross-head portions I3 and Whose head il of the portions i3 to transmit the pull upon the draw-bar Il to the pull-rod I6. The nut Il is so adjusted that the bow-spring 8 will be carried out of contact with the pressure-heads 1. by the weak recovery spring I8 when the strong is engaged by the under faces recovery springs I4 are holding the cross-head |2 in engagement with the stops I5. So far as described, the controller does not diifer essentially from that disclosed in the Chason Patent No. 1,792,818, previously referred to.

Threaded into the end wall I0 coaxially with one of the springs |4 is the threaded shank I9 of an adjustable stop-screw including the knurled head 2D which is accessible to the operator exteriorly of the casing I, 2. The' knurled head 20 is hollow and houses a relatively stiff spring 2| which presses upon the head 22 of a plunger 23 passing longitudinally through the threaded stem I9 and projecting at 24 beyond thel end of the latter and constituting a yielding tip for the adjustable stop-screw'IS, 20. The spring 2| is backed by the breech screw 25. A coil-spring 25 surrounding the exposed portions of the stop-screw stem I9 frictionally holds the stop-screw in any adjusted position. The yielding tip 24 of the stop-screw is in position to be engaged by the downwardly projecting tip I3 of the cross-head I2.

In the operation of the device, the operator exerts a pull upon the draw-bar II until it is perceived by the sense'of feeling that the crosshead I2 has engaged the yielding tip 24 of the stop-screw. If, as is likely, the machine does not start, the operator exerts a further pull upon the draw-bar I I to start the machine; the spring 2| yielding as the tip screw stem I9. After the static friction of the machine has been overcome by the pull of the draw-bar beyond the point where the operator is sensible of the resistance of the yielding stopscrew, the operator relieves the pull upon Vthe draw-bar until it is perceived by the sense of feeling that the draw-bar cross-head is just touching theyielding tip 24 of Vthe stop-screw. This gives the desired slow running speed suitable for embrodering and darning operations. The spring 2| is made stiff enought to enable the operator to readily feel and hold the'position of engagement of the draw-bar head |2 with the yielding tip 24 ywithout compressing such spring. It is not made so stiff,'however, that it is burdensome to the operator to compress it for starting purposes.

The stepless range of speeds made possible by the use of a carbon controller-is particularly advantageous in this connection, in combination with a finely adjustable or screw-threaded yielding stop, as such combination enables any selected operating speed to be closelyfpredetermined and closely held. The construction and location of the stop, relative to the elements of the controller are of advantage in that the stopscrew is readily accessible for adjustment, yet is disposed in a protected position. It is of simple construction and is easily applied to and removed from the controller as a self-contained 24 is forced into the stopunitary assembly without disassembly of any of the controller parts.

The stop-screw I9, 20 may be unscrewed far enough to permit the draw-bar II to be pulled downwardly as far as it will go without engagement of the cross-head I2 with the yielding tip 24. Hence, the stop device may be unsorewed from operative to inoperative position without removing it 'from the controller casing. f While the invention is disclosed in one specific embodiment, as applied to a foot-operated sewing machine motor-controller, it is not to be understood as limited in its broader aspects to a foot-operated controller.

Having thus set forth the nature of the invention, what I claim herein is:-

l. The combination with a carbon compression rheostat having an operating draw-bar movable in one direction by the operator to decrease the electrical .resistance thereof, of an initially disengaged stop-screw disposed in the l path oi and adjustable in the direction of movement of said draw-bar, and spring means permitting said stop-screw to be yieldingly engaged by said draw-bar in the resistance decreasing movement of the latter.

2. The combination with a carbon compression rheostat having an operating draw-bar movable in one direction by the operator to decrease the electrical resistance thereof, of a stop-screw disposed in the path of and adjustable in the direction of movement of said drawbar, said stop-screw having an initially disengaged yielding tip adapted to be engaged by said draw-bar in the resistance decreasing movement of the latter.r Y

3. The combination with a carbon compression rheostat having an operating draw-bar movable inone direction by the operator and a relatively strong recovery spring opposed to the operative force exerted upon the draw-bar by the operator, of an initially disengaged stopscrew disposed in the path of and adjustable in the direction of movement of said draw-bemand spring means permitting said stop-screw to be yieldingly engaged Vby said draw-bar in the resistance decreasing movement of the latter, said spring-means being stiff enough relative to said recovery spring to be perceptibly felt by the operator. f

fi. The combination bon compression rheostat housed'within said casing, a manually operated draw-bar extending into said casing and operatively connected to said rheostat, and an adjustable stop-screw mounted on said casing, said stop-screw having a head accessible to the operator `exteriorly of said casing and a yielding tip within said casing in position to perceptibly resist movement of said draw-bar beyond a predetermined position.

HENRY L. ZABRISKIE.

with a casing, of a car- 

